Maimonides

Silence is a fence around wisdom.

It is natural for a man's character and actions to be influenced by his friends and associates and for him to follow the local norms of behavior. Therefore, he should associate with the righteous and be constantly in the company of the wise, so as to learn from their deeds. Conversely, he should keep away from the wicked who walk in darkness, so as not to learn from their deeds.

For it is said, "You shall strengthen the stranger and the dweller in your midst and live with him," that is to say, strengthen him until he needs no longer fall upon the mercy of the community or be in need.

You are no doubt aware that the Almighty, desiring to lead us to perfection and to improve our state of society, has revealed to us laws which are to regulate our actions. These laws, however, presuppose an advanced state of intellectual culture. We must first form a conception of the Existence of the Creator according to our capabilities; that is, we must have a knowledge of Metaphysics. But this discipline can only be approached after the study of Physics: for the science of Physics borders on Metaphysics, and must even precede it in the course of our studies, as is clear to all who are familiar with these questions.

I rely on two precedents: first, to similar cases our Sages applied the verse, "It is time to do something in honour of the Lord: for they have made void thy law"... Secondly, they have said, "Let all thy acts be guided by pure intentions." ...Lastly, when I have a difficult subject before me—when I find the road narrow, and can see no other way of teaching a well established truth except by pleasing one intelligent man and displeasing ten thousand fools—I prefer to address myself to the one man, and to take no notice whatever of the condemnation of the multitude; I prefer to extricate that intelligent man from his embarrassment and show him the cause of his perplexity, so that he may attain perfection and be at peace.

To give a full explanation of the mystic passages of the Bible is contrary to the law and to reason; besides, my knowledge of them is based on reasoning, not on divine inspiration [and is therefore not infallible]. ...It is... possible that my view is wrong, and that I misunderstand passages referred to. ...Those, however, for whom this treatise has been composed, will, on reflecting on it and thoroughly examining each chapter, obtain a clear insight into all that has been clear and intelligible to me. This is the utmost that can be done in treating this subject so to be useful to all without fully explaining it.

It is man's duty to love and to fear God, even without hope of reward or fear of punishment.

Every one of the six hundred and thirteen precepts serves to inculcate some truth, to remove some erroneous opinion, to establish proper relations in society, to diminish evil, to train in good manners, or to warn against bad habits. All this depends on three things: opinions, morals, and social conduct. ...these three principles suffice for assigning a reason for every one of the Divine commandments.

It is better and more satisfactory to acquit a thousand guilty persons than to put a single innocent one to death.

We are obligated to be more scrupulous in fulfilling the commandment of charity than any other positive commandment because charity is the sign of a righteous man.

Every Israelite has a duty to study whether he is poor or rich, whether healthy or suffering, whether young or very old and in failing strength, even if he is poor and supported by charity or begs from door to door.

After a long time the great and awful Name was forgotten and the people, men, women and children, only recognized an image of wood or stone and the temple of wood or stone which they had been brought up from infancy to serve by bowing down.

By following entirely the guidance of lust, in the manner of fools, man loses his intellectual energy, injures his body, and perishes before his natural time; sighs and cares multiply; there is an increase of envy, hatred, and warfare, for the purpose of taking what another possesses. The cause of all this is the circumstance that the ignorant considers physical enjoyment as an object to be sought for its own sake. God in His wisdom has therefore given us such commandments as would counteract that object, and prevent us altogether from directing our attention to it, and has debarred us from everything that leads only to excessive desire and to lust. This is an important thing included in the objects of our Law.

A person should not eat until his stomach is full. Rather, he should eat until he has consumed approximately three quarters of his fill.

One should not eat unless one is hungry, nor drink unless one is thirsty.

Excessive eating is like a deadly poison to the body and is a principal cause of all illness.

Anyone who lives a sedentary life and does not exercise, even if he eats good foods and takes care of himself according to proper medical principles — all his days will be painful ones and his strength shall wane.

As long as a person exercises, exerts himself greatly, does not eat to the point of being overly full, and keeps his bowels soft, illness will not come upon him and his strength will increase.

No disease that can be treated by diet should be treated with any other means.

The physician should not treat the disease but the patient who is suffering from it.